1. Field of the Invention
This invention relates generally to improvements in a method of and apparatus for turning over sheet articles, and more particularly to apparatus for inverting a glass sheet and placing it on top of another paired sheet.
In the production of bent laminated glass products, such as present-day automobile windshields, it is common practice to achieve the desired configuration by bending flat sheets of glass in pairs to the contour of a mold. Prior to the bending thereof, the sheets are thoroughly cleaned and dried and a surface of at least one and preferably both of the sheets has applied thereto, a coating of a water soluble parting material to prevent the sheets from fusing to one another when heated during the bending process. The sheets are then placed one upon the other with the parting material therebetween and their edges aligned in the preparation for bending.
2. Description of the Prior Art
As disclosed in U.S. Pat No. 3,034,632, issued on May 15, 1962, pairs of glass sheets are carried horizontally or in a flat position on a conveyor through the various steps of the above-mentioned process, which includes inverting the first sheet of each pair and laying it upon the second sheet. In this apparatus, when the first sheet is lifted to a vertical position in the turnover process, it is transferred to and supported by a lowering device until there is a relatively small vertical space between it and the second sheet at which time it is permitted to fall freely upon the second sheet.
In FIG. 6 of the above-mentioned patent, it will be noted that as the first sheet is lifted, it pivots first on its trailing edge on the conveyor and then, as it is lowered toward the second sheet, the pivot is transferred to the front upper edge of the second sheet and the lower surface of the first sheet. This pivoting of the first sheet on the conveyor and then on the second sheet sometimes causes the two sheets to be chipped along their respective edge portions. Also, it will be noted that after the first sheet has been inverted and placed upon the second sheet, their front lateral edges are not aligned as is necessary for further handling of the sheets, necessitating that the sheets be slid relative to each other into a superimposed relationship. This chipping and sliding of the sheets may form internal scratches therebetween which are optically objectionable, resulting in the sheets being rejected and discarded.